Deformylative Intramolecular Hydroarylation: Synthesis of Benzo[e]pyrido[1,2-a]indoles.

Attempted cyclization of indolizines bearing both formyl and alkyne groups under acid catalysis provided benzo[e]pyrido[1,2-a]indoles with an aryl substituent at the C6 position as major products, along with the expected C5-acylated benzo[e]pyrido[1,2-a]indoles as minor ones, which resulted from preferential deformylative intramolecular hydroarylation instead of intended alkyne-carbonyl metathesis.